'To the wild billows it has been said, ‘thus far shalt thou go, and no further; and here shall thy proud waves be stayed.’ Vainly then do they beat and foam, restrained by the power that confines the struggling planets in their orbits, matter yields to the great governing Spirit. But an immortal soul, not restrained by mechanical laws and struggling to free itself from the shackles of matter, contributes to, instead of disturbing, the order of creation, when, co-operating with the Father of spirits, it tries to govern itself by the invariable rule that, in a degree before which our imagination faints, regulates the universe.' - Mary Wollstonecraft, A Vindication of the Rights of Woman